Comment on “Low-dose Extrapolation of Radiation-Related Cancer Risk” The task group report says “The LNT hypothesis, combined with an uncertain DDREF for extrapolation from high doses, remains a prudent basis for radiation protection at low doses and low dose rates”. I speak from 30 years of experience at the nuclear research establishment at Lucas Heights, with the last 13 spent as a tour guide at the same place. I can understand the thinking behind the LNT approach, but disagree with it as a matter of public policy. A major problem with LNT is with its all too literal interpretation by anti-nuclear groups to mean that there is no safe dose of radiation. I have seen scientific papers use the LNT to calculate cancer deaths over the next 10,000 years as a result of Technetium-99 contamination in the Irish Sea, but without mentioning the much larger internal radiation doses from Potassium-40, Carbon-14, uranium thorium and the other natural radioisotopes in the body. My long experience leads me to say that about 98% of the general public I meet does not know that the earth is naturally radioactive. They react with some surprise when informed that they are radioactive too but start to relax when they know it has been around for a very long time. A not uncommon remark is, “But we have been told that there is no safe dose of radiation, but what you tell us means that there must be a safe dose”. The ICRP needs to explain its philosophy to the public in terms which can be understood by the public. A colleague and I were invited to talk to senior engineering students on the topic of nuclear energy about 4 months ago and were faced by the no safe dose hypothesis. It is an issue of public concern which must be addressed by the ICRP. When people learn that the dose limit for the public for exposure is 1mSv/y and that natural background radiation doses in Europe range from 2 in Britain to more than 7 in Finland, they get puzzled. Try explaining it to the public. There is a radiation atlas of European countries which could be used to compare cancer incidence and radiation dose on a large scale and make some estimate of a possible threshold. Would you like my data which suggests a threshold greater than the Finland dose? I am disappointed that the ICRP has stayed in the well worn road of LNT and behind the battlement of statistical difficulty and has not moved in the direction of accepting a threshold dose. Jim Brough, President, Australian Nuclear Forum.